The systematic performance and review of autopsies of bone marrow transplant recipients has proved to be quire helpful in the evaluation and appropriate modification of experimental protocols. The autopsies performed for the John Hopkins Hospital Bone Marrow Transplant Unit differ from routine autopsies in that multiple cultures are performed for infectious agents (virus, fungus, bacteria) and additional biopsies of tissue are evaluated for graft-vs-host disease, immune reconstitution, relapse of leukemia, toxicity, etc. In this proposal, we will continue to perform and review the autopsies as part of the evaluation of the experimental protocol described elsewhere. The specific aims for this section of the core project are: 1. To assist in evaluating the effectiveness of the experimental protocol, such as prevention of relapse of malignancy or prevention of acute and chronic GvHD. 2. Systematic evaluation for complications including infectious diseases and drug toxicity. The autopsies will be reviewed by a single pathologist (WEB) discussed regularly at monthly morbidity and mortality conferences.